The invention arose out of a consideration of the work of Anoto Group AB and others in relation to digital pattern paper and digital pens. It is convenient to discuss the invention in that contextual background, but it will be appreciated that the invention is not restricted to use with any proprietary system.
The prior art Anoto digital pen and paper system is described on their website www.anotofunctionality.com. However, since the content of websites can change with time it is to be made clear that the prior art admitted is that which was published on their website no later than the day before the priority date of this patent application. It is also appropriate to include in this application itself a brief review of the Anoto system.